This invention relates to display devices using magnetic bubbles, and more particularly to a magnetic bubble display device in which, after a bubble grid is formed, the magnetic bubbles in the bubble grid are selectively caused to vanish to display characters, figures or the like.
FIG. 1 shows a conventional magnetic bubble display device. The device has a film made of magnetic bubble material such as rare earth orthoferrite (hereinafter referred to as "a magnetic film"), a conductor wire pattern X consisting of a number of conductor wires S.sub.1 through X.sub.7 each of which is folded in parallel to have a "go" wire and a "return" wire; and a conductor wire pattern Y consisting of a number of conductor wires Y.sub.1 through Y.sub.7 which are folded similarly as in the case of the conductor wire pattern X and laid preferably but not necessarily perpendicularly across the conductor wires X.sub.1 through X.sub.7. First ends of the conductor wires X.sub.1 through X.sub.7 are connected through respective switches S.sub.x1 through S.sub.x7 to an electric source 1. Similarly, first ends of the conductor wires Y.sub.1 through Y.sub.7 are connected through respective switches S.sub.y1 through S.sub.y7 to an electric source 2. A control circuit 3 controls these switches S.sub.x1 through S.sub. x7, and S.sub.y1 through S.sub.y7.
In the conventional device thus organized, currents flowing in the conductor wire patterns X and Y are controlled, to thereby change the strengths of magnetic fields which are created between the conductor wires, whereby magnetic bubbles are generated or caused to vanish individually, to display a desired character or figure. However, the conventional device is disadvantageous in that it is, as a whole, intricate in construction because each conductor wire consists of a "go" wire and a "return" wire. In addition, the conventional device suffers from a drawback that, when it is necessary to increase the number of magnetic bubbles in a line or column direction, since each conductor wire consists of "go" and "return" wires, the length of a conductor wire is increased by twice as long as the distance between picture elements, as a result of which the percentage of resistance increase per picture element is doubled. Furthermore, the direction of current for formation of a bubble grid is opposite to the direction of current for causing magnetic bubbles to vanish. Therefore, different drive transistors must be provided for different current directions. Thus, the number of transistors per line or column is also doubled.